1. Field of the Invention
The present invention relates to foot controllers for dental instruments.
2. Prior Art
In the prior art, this type of foot controller has been equipped with one or two pedals for controlling the rotational speed of the dental handpiece. For filling a tooth, the rotational speed must be adjusted by controlling the foot pressure in accordance with the position being filled and the filling accuracy. Usually, high-speed is utilized for rough filling (rasping) while the low-speed is used for high precision filling. When filling a tooth of a patient lying on his back on a bed, while the operator is sitting on a chair, as in the case of sedentary treatment, because of the operating posture, the operator's foot is automatically stretched forward (to a position in front of and away from the chair where the therapist is sitting) during the rasping by high rotational speed. On the contrary, during precision filling with slower rotation, the operator's foot is automatically placed at a position near the chair.
In this case, in the prior art foot controller, the tread turning position of the operating pedal is fixed to be around the center area. Therefore, care must be taken to move the foot controller itself to a position in front of and away from the chair during rasping while during precision drilling, to move it reversely to a position closer to the chair. Furthermore, during rough filling, the pedal must be stepped on hard in order to provide the high-speed rotation at the point away from and in front of the chair. Combined with the increase in spring tension of the pedal, this operating position intensifies the operator's fatigue with increase in rasping time.